Witness to a Fatality

n2diving

On a pleasant afternoon in March of 2008, off the coast of Hillsboro Beach Florida, I suddenly found myself at the back of a dive boat kneeling over a fellow rebreather diver and administering CPR. The attached PDF of my article contains my opinions and speculation about what happened that day, and is offered to help other rebreather divers understand some of the factors that led to the accident. It assumes the reader is familiar with closed-circuit rebreathers.

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witnesstoafatality.pdf (90.5 KB, 784 views)

Ben Field

Rather frightening reading as usual but thank you for posting.

One comment, regarding this section-
"he did something typical of SCR divers although unnecessary
for CCR divers: he closed the on-board gas supply valves"

You didn't state which model or type of rebreather was in use, you mentioned his training and recent cross over so I wondered if this was a modified SCR? I only ask because modified homebuilds often adopt a KISS style O2 addition system, which requires the diver to close the O2 off between dives to save the gas, unlike a swithced off ECCR, a MCCR(KISS style) will continue to use O2.

(I'm not having a pop at any type of unit merely observing that there is a difference in practice that a pure ECCR diver might not recognize...)

As a consquence most MCCR divers I've met turn off both O2 and Dil between dives.

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www.hugsac.org.uk

CCR-Wrecker

I was thinking the same thing.


regards,
Andy

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"I know what you'll find, it's in your mind, it's what you want to see..." Ozzy

n2diving

The victim was an instructor for the O2ptima eCCR and the Dolphin SCR.
-- Mark

Hanssing

A very sobering read.

I have a hard time seperation your theories from the buddys witness-report, but I can understand some of your conclusions.
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You do not mention the specific equipment, but should not some sort of alarm trigger way before hypoxic levels? Even with a low setpoint of 0.5 an alarm should surely go off at 0.4'ish wich would ensure some time to respond without panic?
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Furthermore I have a hard time seeing why you should leave your eCCR-unit with tanks turned on?
Shutting down completely and doing the same predive-check EVERY time would ensure O2-tank was allways opened. COnsistent behavior between each dive would seem better?

I'm afraid this from a keyboard away looks like eCCR-complacency tragedly again took a divers life.
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Your questions in the end bears reflection:

As an mCCR-diver who is allways forced to shut down O2, and because of auto-shutoff I allways breathe down the loop to 0.21 between dives.
I therefor never breathe from the loop until I have woken my displays confirmed PPO-above 0.21 and injects Oxygen until O2 is above 0.5.
This does not constitute a real prebreathe, however it does verify O2-delivery works, and is pressurised. I cannot skip theese steps, as I will not have a vaible PPO - how to force this onto an eCCR?

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Thanks for your sobering acticle.

Nicolai

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Woohooo - I can change my rEvo!
Its going to be bitchin' tricked out piece of gear

UWshutterbug

Yes very sobering indeed. As one of my former tech instructors told me “under stress, the average person, when given a 50/50 chance of getting it right, they will inadvertently get it 90 percent wrong.”

Walt Stearns
Editor-in-Chief
Underwaterjournal

tflaris

Thanks for the article. A wake-up call for me to stay prudent.

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"Except for this one, I have come to the conclusion that all generalizations are false" -Jim Hayes

UWSojourner

Thanks for posting the report ... sobering to say the least.

FWIW ... in addition to the check list, a mnemonic I like is GASP. GASP when gearing up and going on loop, at water entry before descending and frequently throughout dive.

G = Gas on ... is it? Check gauges, etc.

AS = Analyze setpoint ... what am I breathing? Is my setpoint correct? Are electronics functioning?

P = prebreathe ... at depth it becomes "preBREATHE" with emphasis on how is my breathing pattern ... too fast ... too shallow ... ok?

Obviously the vision of gasping helps communicate to my thick head the critical nature of the checks. Everytime I stick the DSV in my mouth I GASP. I'm sure others have their own reminders ... like I said, FWIW.

tibby

Thanks for thking the time to write this. Very good reminder.
Tibby

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Does the voice of reason change when you add helium to the mix?...hmm

Pawel Szopinski

Thanks for the report.

It's amazing how many people die because they don't know what they are breathing.

This accident could have been avoided just by monitoring PO2 and gas.

Regular look at the gauges and displays even before you enter the water could have saved some many lives.